As Pyongyang and Washington traded threats, Russia and China weighed in.
In Moscow, Russian Foreign Minister Sergei Lavrov said on Friday that risks of a military conflict over North Korea's nuclear program are very high and Moscow is deeply worried by the threats from Washington and Pyongyang.
Lavrov encouraged Pyongyang and Washington to sign up to a joint Russian-Chinese plan, under which North Korea would freeze its missile tests and the United States and South Korea would impose a moratorium on large-scale military exercises.
"The side that is stronger and cleverer" should take the first step to defuse the crisis, said Lavrov, speaking live on state television at a forum for Russian students.
Earlier in Beijing, a Chinese state-run newspaper said on Friday that China should remain neutral if North Korea launches an attack that threatens the United States, sounding a warning for Pyongyang over its plans to fire missiles near the U.S. Pacific territory of Guam.
Asian equity markets sank again on Friday and European stocks looked set for their worst week this year because of the tensions. [MKTS/GLOB]
"This situation is beginning to develop into this generation's Cuban Missile crisis moment," ING's chief Asia economist, Robert Carnell, said in a research note. "While the U.S. president insists on ramping up the war of words, there is a decreasing chance of any diplomatic solution."
China, North Korea's most important ally and trading partner, has reiterated calls for calm. Beijing has expressed frustration with both Pyongyang's repeated nuclear and missile tests and with behavior from South Korea and the United States, such as military drills, that it sees as increasing tensions.
"China should also make clear that if North Korea launches missiles that threaten U.S. soil first and the U.S. retaliates, China will stay neutral," the Global Times, which is widely read but does not represent government policy, said in an editorial.
"If the U.S. and South Korea carry out strikes and try to overthrow the North Korean regime and change the political pattern of the Korean Peninsula, China will prevent them from doing so," it said.
China's Foreign Ministry repeated a call for all parties to speak and act cautiously and do more to ease the situation, rather than going down the "old path" of exchanges of shows of force and continually rising tension.
North Korea's state-run KCNA news agency said on Thursday its army would complete plans in mid-August to fire four intermediate-range missiles over Japan to land near Guam.
Trump said Kim was not going to get away with his "horrific" comments and disrespecting America.
"Let's see what he does with Guam. He does something in Guam, it will be an event the likes of which nobody's seen before, what will happen in North Korea," Trump told reporters on Thursday in New Jersey, without offering specifics.
The United States and South Korea remain technically still at war with North Korea after the 1950-53 Korean conflict ended with a truce, not a peace treaty.